[PATCH AUTOSEL 6.6 35/38] cifs: do not search for channel if server is terminating

Sasha Levin
2024-02-07T21:24:48Z

From: Shyam Prasad N <sprasad@microsoft.com>

[ Upstream commit 88675b22d34e6e815ad4bde09c590ccb2d50c59d ]

In order to scale down the channels, the following sequence
of operations happen:
1. server struct is marked for terminate
2. the channel is deallocated in the ses->chans array
3. at a later point the cifsd thread actually terminates the server

Between 2 and 3, there can be calls to find the channel for
a server struct. When that happens, there can be an ugly warning
that's logged. But this is expected.

So this change does two things:
1. in cifs_ses_get_chan_index, if server->terminate is set, return
2. always make sure server->terminate is set with chan_lock held

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/smb/client/sess.c | 4 ++++
fs/smb/client/smb2pdu.c | 2 +-
2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/smb/client/sess.c b/fs/smb/client/sess.c
index 62596299a396..2b49a3646fbd 100644
--- a/fs/smb/client/sess.c
+++ b/fs/smb/client/sess.c
@@ -75,6 +75,10 @@ cifs_ses_get_chan_index(struct cifs_ses *ses,
{
unsigned int i;

+ /* if the channel is waiting for termination */
+ if (server->terminate)
+ return CIFS_INVAL_CHAN_INDEX;
+
for (i = 0; i < ses->chan_count; i++) {
if (ses->chans[i].server == server)
return i;
diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index ab8765113392..bd2822ad9b22 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -178,6 +178,7 @@ cifs_chan_skip_or_disable(struct cifs_ses *ses,
}

ses->chans[chan_index].server = NULL;
+ server->terminate = true;
spin_unlock(&ses->chan_lock);

/*
@@ -188,7 +189,6 @@ cifs_chan_skip_or_disable(struct cifs_ses *ses,
*/
cifs_put_tcp_session(server, from_reconnect);

- server->terminate = true;
cifs_signal_cifsd_for_reconnect(server, false);

/* mark primary server as needing reconnect */
--
2.43.0